You may see, hear, taste, touch, or even smell something that will inspire you to write. It maybe a person in your life, or person you would like to meet. I could be phrase you overheard or feeling you once had, but is magical. It’s magical because you weren’t thinking about writing a song, but you were inspired to write.
Putting your thoughts into rhyme is just practice. Some people have the gift of rhyme. I don’t. I have to work at it. Don’t under estimate your abilities. It’s like everything else in life. You have to work at it to make it a success. If it were easy, everyone would be doing it.
I have written lyrics for people that provided me the music or the idea. I really don't think there is much different for me, but when I write for myself I start with the lyrics. I fall in love with the lyrics of songs I heard long before I enjoy the music.
I don't know if this has helped you with your writing, but it may help you to understand the magic of song writing.
Just remember not to take anything I say to serious. I a little looney don't ya know!